Контент по центру формы

Autorization_Yurevich/MainWindow.xaml

@@ -7,6 +7,15 @@
         mc:Ignorable="d"
         Title="MainWindow" Height="450" Width="800">
     <Grid>
-        
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="235"/>
+            <RowDefinition Height="*"/>
+        </Grid.RowDefinitions>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="*"/>
+            <ColumnDefinition Width="295"/>
+            <ColumnDefinition Width="*"/>
+        </Grid.ColumnDefinitions>
     </Grid>
 </Window>